The GELLAB-II software system, http://www-lecb.ncifcrf.gov/lemkin/gellab.html, is an exploratory data analysis system for the analysis of sets of 2D electrophoretic protein gel images written in UNIX. It incorporates sophisticated subsystems for image acquisition, processing, database manipulation, graphics and statistical analysis. It has been applied to a variety of experimental systems in which quantitative and qualitative changes, in one or more proteins among hundreds or thousands of unaltered proteins, is the basic analytic problem. Keeping track of changes detected using these methods is also a major attribute of the system. A composite gel database may be viewed under different exploratory data analysis conditions, and statistical differences and subtle patterns elucidated from slices of an effective 3D database. Results can be presented in a variety of tables, plots or derived images and on workstations over wide area networks. The GELLAB-II research has resulted in a technology transfer CRADA with CSPI/Scanalytics Inc., for a commercially available system GELLAB-II+, making this technology easily available to cancer researchers on inexpensive Microsoft Windows PCs (released in 1996). Such commercialization resulted in wider use and better support of the GELLAB-II technology than we could provide.